Flashtube lamp unit



June 28, 1955 E. B. NOEL 2,712,095

FLASHTUBE LAMP UNIT Filed June 24, 1952 Invent/or. Edward B. Nol

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His Atto Hey FLASHTUBE LAMP UNIT Edward E. Noel, Cleveland Heights,Ohio, assignor to General Electric Company, a corporation of New YorkApplication June 24, 1952, Serial No. 295,207

Claims. (Cl. 31557) The present invention relates to lamp unitsincorporating a fiashtube for use in photography and its principalobject is to provide a compact unit of this type having a short lightcenter length, positive starting characteristics, a high light outputand a rugged structure. Funther objects and advantages of the inventionwill appear from the following detailed description of species thereof.

Flashtubes require the application of a starting potential thereto toinitiate the high voltage discharge between the main electrodes mountedat the ends of the tube. The starting potential is usually applied by anexernal electrode, known as the triggering electrode, engaging thetubular envelope of the fiashtube and a transformer, known as thetriggering coil, is used for supplying the required starting potential.According to the present invention improved results are obtained by aconstruction wherein the triggering electrode and the triggering coilare mounted within the turns of a helically coiled flashtube andconstitute part of a support for the fiashtube Within the lighttransmitting jacket.

In the drawing accompanying and forming part of this specification anembodiment of the invention is shown, in which:

Fig. 1 is a perspective, partly sectional view of the lamp unit as seenfrom above with parts thereof broken away to show the internalstructure;

Fig. 2 is a front elevational, partly sectional view on an enlargedscale of the flashtube support and starting apparatus for the flashtubeshown in Fig. 1; and

Fig. 3 is a top plan view of the flashtube support shown in Figs. 1 and2.

The lamp unit shown in the drawing comprises a tubular outer glassjacket 1 closed at one end and having its open end closed by a discshaped base 2 of electrically insulating material, such as a ceramicmaterial. The base 2 has a flange 3 which is cemented to the open end ofthe jacket 1. Three metal contact pins 4, 5 and 6 are secured to andproject outwardly from the base 2 for connection to a power source. Thebase 2 is formed with an integral hollow centering pin 7.

The lamp unit also comprises a helically coiled fiaslrtube 8 which issupported within the glass jacket 1 by a metal rod 9 having one endcemented into the hollow centering pin 7 of the base 2. The fiashtube 8is provided with electrical terminals 10 and 11 in the form of currentinlead wires sealed into and extending outwardly from the ends of itshelically coiled tubular glass envelope 12.

The structure for supporting the flashtube 8 within the jacket 1includes, in addition to the base 2 and the rod 9, a triggering coil 13in the form of a cylindrical transformer having a tubular core 14 ofsintered metal powder which is mounted around and attached to the rod 9at a portion of the rod near its inner end. The supporting structurealso includes a triggering electrode in the form of metal sleeve 15,such as an aluminum sleeve, mounted around, gripping and frictionallyengagnited States Patent 0 2,712,095 Patented June 28, 1955 ing thetransformer 13. The sleeve is split longitudinally as shown at '16 inFig. 3 to facilitate its mounting on the coil 13 and also to prevent ashort circuiting turn effect. The sleeve 15 has outwardly curved supporttabs 17 at each of its ends which engage the end turns of the helicalflashtube 8 as shown in Fig. 1. The flashtube 3 thus is supportedaxially with the jacket 2 and all the turns of the helically coiledglass envelope 12 of the fiashtube are in contact with the metal sleeve15.

The large area of contact between the sleeve 15 and the fiashtubeenvelope 1'2 facilitates starting of the discharge between the maindischarge supporting electrodes mounted in the ends of the envelope 12and the starting or triggering voltage required is substantially lowerthan that required when the triggering electrode is in the form of theusual thin wire wound on the turns of the fiashtube, and having arelatively small area of contact therewith. The triggering coil 13supplying the triggering voltage thus may be of small size suitable formounting within the turns of the helically coiled tube 12.

The electrical connections between the various electrical elements ofthe lamp unit are made through the usual current lead wires. The rod 9is connected to the contact pin 5 by the lead 13, to one side of theprimary 19 of the trigger coil 13 by the lead 20, and to the terminalIt? at the anode end of the fiashtube by the lead 21. The support rod 9thus serves as a common, low voltage lead for the flashtube 8 and thetrigger coil 13.

The lead 22 of the other side of the primary 19 of the trigger coil 13is attached to the contact pin 6 on the base 2. The terminal 11connected to the cold cathode 23 of the flashtube is connected to thecontact pin 4 on the base 2 by the short, high voltage lead 24. Theshort lead 24 is widely separated from the outer leads to avoidfiashovers therebetween. The sleeve 15 is connected to the secondary 25of the trigger coil 13 by the lead 26.

The above connections are made by soldering or welding the leads to thevarious metal parts.

The outer surface of the sleeve 15 is smooth to reflect outwardly of thelamp unit the light incident thereon from the fiashtube 8.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A lamp unit comprising in combination, a tubular glass jacket havingone open end, a helically coiled flashtube and a support for saidfiashtube in said jacket, said support comprising an insulating baseprovided with electrical contacts and closing the open end of saidjacket, said base having also an externally protruding hollow centeringpin, a support rod having one end secured within said centering pin andextending from said base axially inward of said jacket, a trigger coilmounted on the inner end portion of said rod and a metal sleeve aroundand gripping said trigger coil, said sleeve being electrically connectedto said coil to serve as a trigger electrode and having at each end aplurality of tabs engaging an outer turn of said flashtube, rality oftabs engaging an outer turn of said flashtube, the said tabs on saidsleeve holding said flashtube with the turns thereof in contact with thesaid sleeve to facilitate ignition of the discharge in said fiashtube,said lamp unit comprising also electrically conducting means connectingsaid trigger coil and said flashtube to said base contacts.

2. A lamp unit comprising in combination, a tubular glass jacket havingone open end, a helically coiled flashtube and a support for saidfiashtube in said jacket, said support comprising an insulating baseprovided with electrical contacts and closing the open end of saidjacket, said base having also an externally protruding hollow centeringpin, a support rod having one end secured within said centering pin andextending from said base axially inward of said jacket, a trigger coilmounted on the inner end portion of said rod and a metal sleeve aroundand gripping said trigger coil, said sleeve being electrically connectedto said coil to serve as a trigger electrode and having at each end aplurality of tabs engaging an outer turn of said fiashtube, the saidtabs on said sleeve holding said flashtube with the turns thereof incontact with the said sleeve to facilitate ignition of the discharge insaid fiashtube, said lamp unit comprising also electrically conductingmeans connecting said trigger coil and said fiashtube to said basecontacts, said support rod being electrically connected to one of saidcontact pins, to a terminal of said fiashtube and to one side of theprimary of said trigger coil to serve as a common lead therefor.

3. In a lamp unit comprising a glass jacket and a helical fiashtubewithin the jacket, a support for the flashtube comprising a support rod,a trigger coil around and attached to said rod and a trigger electrodearound and attached to said coil, said trigger electrode being alongitudinally split metallic sleeve, said fiashtube being mountedaround said sleeve, said support comprising also a lead connecting oneside of the primary of said coil to said support rod and a lead attachedto and extending from said rod for connection to a terminal or" saidfiashtube.

4. A lamp unit comprising in combination, a glass jacket, a helicallycoiled flashtube having electrodes at its ends, and electricallyconducting means supporting said fiashtube in said jacket, said meanscomprising a trigger coil and a trigger electrode around said coil andelectrically connected thereto, said trigger electrode being alongitudinally split metallic sleeve, said flashtube being mounted onand around said sleeve.

5. A lamp unit comprising in combination, a glass jacket, a helicallycoiled fiashtube having electrodes at its ends, and electricallyconducting means supporting said fiashtube in said jacket, said meanscomprising a trigger coil and a trigger electrode around said coil andelectrically connected thereto, said trigger electrode being alongitudinally split metallic sleeve having a reflecting outer surface,said flashtnbe being mounted on and around said sleeve.

References Cited in the file of this patent UNlTED STATES PATENTS1,963,963 Barclay June 26, 1934 2,492,619 Casellini Dec. 27, 19492,624,858 Greenlee Jan. 6, 1953

